As for the recording method by means of an inkjet printer which is one of the typical methods among various color recording methods, various methods for discharging ink have been developed. In any of said discharging methods, ink droplets are generated and adhered onto various record-receiving materials (such as paper, film and cloth) to perform recording. This method has been rapidly prevailing lately and is expected to continue growing remarkably in the future because of features such as quietness without noise generation due to no direct contact of a recording head with a record-receiving material and as easiness in downsizing, speeding up and colorizing. Conventionally, as an ink for fountain pens, felt-tip pens or the like and as an ink for inkjet recording, inks where a water-soluble dye is dissolved in an aqueous medium have been used. In these water-based inks, a water-soluble organic solvent is generally added to prevent ink from clogging at a pen tip or an inkjet nozzle. These inks are required to provide recorded images with sufficient density, not to clog at a pen tip or a nozzle, to dry quickly on a record-receiving material, to bleed less, to have excellent storage stability, and so on. In addition, recorded images formed with said ink are required to have fastnesses such as water fastness, moisture fastness, light fastness and gas fastness.
Clogging at the nozzle of an inkjet is often due that water in an ink evaporates around the nozzle before the other solvent and additive do, resulting in the compositional condition that water remains less while the other solvent and additive remain more whereby the coloring matter solidifies and precipitates. Therefore, it is one of the very important performances required that solids hardly precipitate even when the ink is concentrated by evaporation of water from ink. For this reason, high solubility in solvents and additives is one of the properties required for coloring matters.
Meanwhile, in order that images or character information on a color display of a computer are recorded in color by an ink jet printer, subtractive color mixing of 4 color inks of yellow (Y), magenta (M), cyan (C) and black (K) is generally used, by which recorded images are expressed in color. In order that images by additive color mixing of red (R), green (G) and blue (B) on CRT (cathode ray tube) displays and the like are, as faithfully as possible, reproduced with images by subtractive color mixing, it is desired that coloring matters to be used for inks, particularly Y, M and C, have respectively a hue close to each standard and also are vivid. In addition, it is required that the inks are stable in storage for a long period of time, and that images printed have a high concentration and also the printed images are excellent in fastnesses as described above.
With the recent development of the inkjet techniques, improvement of printing speed in inkjet printing is remarkable. Consequently, there is a move to use an inkjet printer, as well as a laser printer using an electronic toner, for document printing on plain paper which is a major application in the office environment. The inkjet printer has some such advantages that there is no need to select the recording paper type and inkjet printers are comparatively inexpensive, and therefore it is becoming widespread particularly in small to medium scale office environments such as SOHO. When an inkjet printer is thus used for printing on plain paper, there is a tendency that hue and water fastness are more emphasized among the qualities required for printed matters. In order to satisfy these performances, a method using a pigment ink has been proposed. However, compared with dye ink, using pigment ink tends to cause such problems that the stability of the ink is poor and the nozzle of a printer head is clogged. In addition, when a pigment ink is used, the low abrasion resistance of printed images is often regarded as a problem, too. It is said that dye ink relatively hardly causes such problems that pigment ink does because dye as a coloring matter component is dissolved in ink. However, dye ink is significantly inferior in water fastness compared with pigment ink, whereby improvement thereof is strongly desired.
As a water-soluble cyan coloring matter used for an ink suitable for inkjet recording, phthalocyanine coloring matter and triphenylmethane-based coloring matter are representative. A typical phthalocyanine coloring matter which is the most widely reported and used includes phthalocyanine derivatives and the like classified into the following A to H.    A: Known phthalocyanine coloring matter such as known as color index C.I. numbers of Direct Blue 86, Direct Blue 87, Direct Blue 199, Acid Blue 249 or Reactive Blue 71 and the like.    B: Phthalocyanine coloring matter such as described in Patent Literatures 1 to 3 and the like [for example, a mixture of Cu-Pc-(SO3Na)m(SO2NH2)n: m+n=1 to 4].    C: Phthalocyanine coloring matters described in Patent Literature 4 and the like [for example, Cu-Pc-(CO2H)m(CONR1R2)n: m+n=a number of 0 to 4].    D: Phthalocyanine coloring matter such as described in Patent Literature 5 and the like, [for example, Cu-Pc-(SO3H)m(SO2NR1R2)n: m+n=a number of 0 to 4 and m≠0].    E: Phthalocyanine coloring matter such as described in Patent Literature 6 and the like, [for example, Cu-Pc-(SO3H)l(SO2NH2)m(SO2NR1R2)n: l+m+n=a number of 0 to 4].    F: Phthalocyanine coloring matter such as described in Patent Literature 7 and the like, [for example, Cu-Pc-(SO2NR1R2)n: n=a number of 1 to 5].    G: Phthalocyanine coloring matter such as described in Patent Literatures 8, 9, and 12 and the like, [a phthalocyanine compound where the substitution position of a substituent is controlled, and a phthalocyanine coloring matter where a substituent is introduced at the beta-position].    H: Benzopyridoporphyrazine-based coloring matter having a nitrogen-containing heterocyclic ring such as a pyridine ring, such as described in Patent Literatures 10, 13, 14 and 15 and the like.
In addition, many proposals have been made to the problem of improvement of water fastness on plain paper through the ages. As a blue coloring matter for inkjet which is excellent in water fastness and whose hue and light fastness are improved, for example, C.I.Direct Blue 86 and C.I.Direct Blue 199 described in Patent Literature 16 are proposed.
As for the dye described in Patent Literature 1, the water fastness thereof is excellent on certain kinds of plain paper but it cannot be said that it is excellent on various kinds of plain paper available on the market, whereby the applicable range is narrow. Therefore, a cyan coloring matter which has an excellent water fastness uniformly on more kinds of plain paper and is also excellent in light fastness, hue and color density has been required.
The Benzopyridoporphyrazine-based coloring matters having a nitrogen-containing heterocyclic ring and a benzene ring disclosed in Patent Literatures 10, 13, 14 and 15 and the like are ones to which active gas fastness, light fastness, moisture fastness, hue and the like are imparted, but improvement of water fastness on plain paper is not mentioned in any of them.
[Patent Literature 1]
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